Recent developments in wireless communications technologies have allowed expansion of service offerings from the original voice telephone service model to include a number of services supporting packet data communications, including for broadband applications. As customers become increasingly familiar with data services offered through landline networks, they are increasingly demanding comparable data communications in the wireless domain, for example to maintain service while mobile subscribers roam freely or to provide remote service in locations where wireless loops are preferable to landline subscriber loops. A number of technologies support packet data communications in the wireless domain.
Under the currently proposed W-CDMA technical specification, there is a dedicated transport channel, the Dedicated Channel (DCH), which can be either a downlink or an uplink transport channel. The DCH is the channel of choice in services where long delays cannot be tolerated, e.g. for low delay constrained packet services and services which require longer than 640 ms packet transmission times. The DCH is also the preferred channel for certain network protocol methods, like TCP/IP, which operate much more efficiently under small packet delays rather than long ones.
However, the current uplink DCH, as with any circuit-switched packet channel, requires a lot of overhead resources. As shown in FIG. 17, under the current uplink DCH method, once a link is set up between a user j and the base station, the communication will require an associated uplink physical dedicated channel (Associated UL-PDCH) and an associated downlink physical dedicated channel (Associated DL-PDCH) for closed-loop power control. When communications for the user j start on these two associated channels, there is a period of time when the base station is still attempting to lock in on the Associated UL-PDCH from user j, during which no data can be transferred to the base station yet. This period of time is called the set-up time. The length of this delay is indeterminate and varies depending on how long it takes for the base station to lock onto the Associated UP-PDCH. After the data is sent from user j to the base station, there is again a period of time called the inactivity time before the two associated channels are released. Also, under the current uplink DCH method, while the data is power-controlled, it does not adapt its modulation, coding and channelization code according to the quality of the link, resulting in additional wastage.
Hence a need exists for a technique to deal with these deficiencies in the current uplink DCH.